• Journal of Marine Life Science
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• v.7 no.2
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• pp.145-153
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• 2022

Mercury (Hg) is a major concern in marine environment because of their bioaccumulation and biomagnification properties, and adverse effects to aquatic organisms at even a trace amount. However, little information on the effects of Hg, compared to other heavy metals, is available in marine small crustaceans. Here, we investigated the transcriptional modulation of metabolism-related genes in the brackish water flea, Diaphanosoma celebensis after exposure to sublethal concentration (0.2, 0.4, 0.8 ㎍/l) of HgCl₂ for 48 h. Relative mRNA expression levels of five detoxification enzyme-coding genes (cytochrome P450; cyp360A1, cyp361A1, cyp4AP3, cyp4C122, and cyp370C5) and six digestive enzyme-coding genes [alpha amylase (AMY), alpha amylase related protein (AMY-like), trypsin (TRYP), chymotrypsin-like protein (CHY), lipase (LIP), pancreatic lipase-related protein (PLRP)] were analyzed using quantitative real time reverse transcription polymerase chain reaction (qRT-PCR). As results, Hg increased the mRNA level of cyp370C5 (clan2) and cyp4AP3 (clan4) in a concentration dependent manner. A significant increase in TRYP mRNA was also concentration-dependently observed after exposure to Hg. These findings suggest that cyp370C5 and cyp4AP3 play a key role in Hg detoxification in D. celebensis, and Hg can affect energy metabolism by modulating the transcription of digestive enzyme. This study will provide better understanding the molecular effects of Hg in marine small crustacean.

• Korean Journal of Environmental Biology
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• v.39 no.3
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• pp.390-398
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• 2021

In this study, the toxicity of chlorothalonil was investigated using survival rate and population growth rate of a marine rotifer, Brachionus plicatilis, typically used in live food in marine aquaculture systems. The survival rate of B. plicatilis was determined after 24 h of exposure to chlorothalonil (0.010-0.156 mg L^-1). Population growth rate of B. plicatilis was calculated after 72 h of exposure to chlorothalonil (0.078-1.250 mg L^-1). The survival rate and population growth rate of B. plicatilis exposed to chlorothalonil in single-dose toxicity assessment showed concentration-dependent reductions. Survival rates of B. plicatilis exposed to chlorothalonil had the following values: NOEC, 0.020mg L^-1; LOEC, 0.039 mg L^-1; and EC₅₀, 0.057 mg L^-1. Population growth rate of B. plicatilis exposed to chlorothalonil had the following values: NOEC, 0.156 mg L^-1; LOEC, 0.313 mg L^-1; and EC₅₀, 0.506 mg L^-1. When the residual concentration of chlorothalonil in the marine coastal area was more than 0.039 mg L^-1, it had a toxic effect on B. plicatilis, a zooplankton. This paper provides toxicity values that can be used as baseline data for organizing environmental standards of chlorothalonil. It also provides insight into toxic effects of chlorothalonil on other non-target organisms.

• Food Science and Industry
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• v.51 no.4
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• pp.278-301
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• 2018

Although more than 80% of living organisms are found in marine ecosystems, only less than 10% of marine resources have been utilized for human food consumptions and other usages. It is well known that marine resources (fish, shellfish and algae) have exceptional nutritional properties; however, their functional characteristic has not been completely discovered. It is believed that metabolites (organic compounds, proteins, peptides, lipids, minerals, etc.) play an important role to show its biological properties. Marine proteins and peptides are considered to be future drugs due to their excellent biological activities with a fewer adverse side effect. Marine peptides show several biological activities, including antimicrobial, antioxidant, anti-inflammatory, anti-cancer, anti-viral, anti-tumor, anti-diabetic, anti-hypertensive, anti-coagulant, immunomodulatory, appetite suppressing and neuroprotective effects. Therefore, the pharmaceutical, nutraceutical, and cosmeceutical companies have been paid attention to the marine peptides to commercialize into products. This current review mainly focused on the above mentioned biological activities of marine peptides and protein hydrolysates as a functional food and pharmaceutical applications. To commercialize these materials in industrial level required large quantity in high-purity level, and it is complicated to produce huge quantity from the marine resources due to insufficient raw materials, unavailability of raw materials through a year, hinder the growth with geographical variations, and availability of compounds in extreme small quantities. The best solution for these issues is to introduce new modern technologies such as artificial intelligence robots, drones, submersibles and automated raw material harvesting vessels in farming industries instead of man power, which will lead to 4th industrial revolution.

• Journal of Microbiology and Biotechnology
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• v.19 no.10
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• pp.1206-1212
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• 2009

Growth rates, photosystem II photosynthesis, and the levels of chlorophyll $\alpha$ and secondary metabolites of Chlorella ovalis were estimated to determine if they were enhanced by the addition of swine urine (BM) or cow compost water (EP) that had been fermented by soil bacteria to deep seawater (DSW) in an attempt to develop media that enabled batch mass culture at lower costs. Growth of C. ovalis in f/2, f/2-EDTA+BM60%, DSW+BM30%, and DSW+EP60% was enhanced and maintained in the log phase of growth for 16 days. The cell densities of C. ovalis in DSW+EP60% ($4.1{\times}10^6$ Cells/ml) were higher than those of f/2 ($2.9{\times}10^6$ Cells/ml), f/2-E+BM60% ($3.7{\times}10^6$ Cells/ml), and DSW+BM30% ($2.7{\times}10^6$ Cells/ml). The growth rate was also more favorable for C. ovalis cultured in DSW+EP60% ($0.15\;day^{-1}$) than that of C. ovalis cultured in the control medium (f/2) ($0.12\;day^{-1}$). Furthermore, the chlorophyll a concentration of C. ovalis cultured in DSW+EP60% (4.56 mg/l) was more than 2-fold greater than that of C. ovalis cultured in f/2 (2.35 mg/l). Moreover, the maximal quantum yields of photo system II at 470 nm (Fv/Fm) were significantly higher in organisms cultured at f/2-E+BM60% (0.53) and DSW+EP60% (0.52) than in the other treatment groups. Finally, Fourier transformation infrared (FT-IR) spectroscopy revealed that C. ovalis grown in DSW+EP60% had more typical peaks and various biochemical pool shifts than those grown in other types of media. Taken together, the results of this study indicate that the use of DSW+EP60% to culture C. ovalis can reduce maintenance expenses and promote higher yields.

• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.138-146
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• 2006

The effects of night-lights on feeding by the black rockfish Sebastes inermis in the cage of the Tongyeong marine ranching area were investigated by analyzing the stomach contents of 200 individuals from July 2004 to August 2004. In night-lights groups, black rockfish consumed mainly copepoda, amphipoda and polychaeta; also those in control area fed on copepods, amphipods and polychaets. Copepods (57%) and amphipods (32%) were the major prey organisms for all study period in night-lights. While, major prey items in control area were copepods (88%). Growth of the black rockfish reared in night-lights conditions were significantly higher than that of those in control area.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.1
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• pp.41-48
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• 2017

Encircling gill net fishery is a kind of gill net which is generally used in shallow coastal waters. After the fish have been encircled by the gill net, noise stimulus such as a stone or sound is used to force them to gill or entangle themselves in the netting surrounding them. Although the fishing by a stone is a traditional fishing method, it is considered as an illegal fishing method by physical stimulus such as explosives and mechanical vibrator. However, this illegal fishing method has raised some problems to the fishing boat of other fisheries or many anglers due to disturb aggregating fish schools. This study is aimed to provide scientific base data to verify whether to impact the ecosystem caused by this encircling gill net. This study exhibited that the impulse noise by concrete sphere in the encircling gill net was $159dB/{\mu}Pa$, the ambient noise from ship engine was $160dB/{\mu}Pa$, and the maximum noise from continuous artificial vibrator was $175dB/{\mu}Pa$. These may be stimulus to the escape of fish distributed in a wide area in its natural state; it is not likely the cause of death due to catastrophic stress. Therefore, it needs to prepare the consideration of standard limit on fishing stimulus in fishing methods of the fishery laws and regulations, prevent fishermen form using illegal fishing gear (i.e. explosive sound standards: $200{\sim}220dB/{\mu}Pa$ and provide them with countermeasures.

• Ocean and Polar Research
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• v.39 no.1
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• pp.35-43
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• 2017

Concentrations of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), dissolved organic phosphate (DOP), and colored dissolved organic matter (CDOM) were measured in the coastal sea off inland aqua farms in northeastern Jeju Island in summer 2015. The highest concentrations of DOC, DON, and DOP were revealed in the surface water off Hado-ri where the lowest salinity conditions prevailed (31.6). The concentrations of DOC, DON, and DOP in the surface water were lower in the inner stations (SH1-1, 1-2, and 1-3) near the aqua farms of the Haengwon-ri than in the outer stations. The concentrations of DOC, DON, and DOP negatively correlated with salinity. These results indicate that the contribution of dissolved organic matter (DOM) from the aqua farms seems to be not significant. On the other hand, the higher concentrations of DON and DOP in the inner stations of Hado-ri (HD 1-1) seem to be attributed to excrement of migrating birds. The three components of CDOM (T, M, and C peaks) showed no relationship with salinity, perhaps due to various in situ productions by marine organisms and decomposition by ultraviolet radiation. The observed lower C:M ratio, an indicator of terrestrial source, and the higher biological index (BIX) of CDOM in the station off Hado-ri indicate that DOM is produced mainly by biological activity. Based on the higher humification index (HIX) of CDOM and the higher DOC:DON ratio off Haengwon-ri, refractory DOM in the inland aqua farms is likely transported to the coastal sea.

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.651-660
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• 2006

Natural products are a rich source of biologically active small molecules and a fertile area for lead discovery of new drugs [10, 52]. For instance, 5% of the 1,031 new chemical entities approved as drugs by the US Food and Drug Administration (FDA) were natural products between 1981 and 2002, and another 23% were natural product-derived molecules [53]. These molecules have evolved through millions of years of natural selection to interact with biomolecules in the cells or organisms and offer unrivaled chemical and structural diversity [14, 37]. Nonetheless, a large percentage of nature remains unexplored, in particular, in the marine and microbial environments. Therefore, natural products are still major valuable sources of innovative therapeutic agents for human diseases. However, even when a natural product is found to exhibit biological activity, the cellular target and mode of action of the compound are mostly mysterious. This is also true of many natural products that are currently under clinical trials or have already been approved as clinical drugs [11]. The lack of information on a definitive cellular target for a biologically active natural product prevents the rational design and development of more potent therapeutics. Therefore, there is a great need for new techniques to expedite the rapid identification and validation of cellular targets for biologically active natural products. Chemical genomics is a new integrated research engine toward functional studies of genome and drug discovery [40, 69]. The identification and validation of cellular receptors of biologically active small molecules is one of the key goals of the discipline. This eventually facilitates subsequent rational drug design, and provides valuable information on the receptors in cellular processes. Indeed, several biologically crucial proteins have already been identified as targets for natural products using chemical genomics approach (Table 1). Herein, the representative case studies of chemical genomics using natural products derived from microbes, marine sources, and plants will be introduced.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.3
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• pp.134-139
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• 2005

The purpose of this study is to quantify the penetration behavior of spilled weathered oil and dispersed oil and to evaluate the influence of the penetrated oils on seawater infiltration in tidal flat environment. The penetration depths of the spilled oils into the tidal flat sediments were gradually deeper according to increase the stranded oil volume. The penetration depth of stranded oil were abruptly dropped at first falling tide, but were not significantly fluctuated after that. Moreover, hydrocarbon concentration was most high within the upper 2 cm. Seawater infiltration was decreased in proportion to the stranded oil volume. Dispersed oil was easily permitted the seawater infiltration than weathered oil and crude oil. Therefore, quick cleaning actions fur penetrated oil will be required far recovery of seawater infiltration, because the seawater contains oxygen and nutrients required for the survival of benthic organisms in tidal flat.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.5
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• pp.411-422
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• 1986

Diets of the rock trout, Agrammus agrammus, in the shore area of Tongbaeksom, Pusan over the period of July 1981 to June 1982 were studied. Specimens were sampled by angling. Stomach analysis showed that the rock trout fed mainly on epibenthic food in the littoral zone along the coast of Tongbaeksom. The food organisms of the enviornment were studied by means of underwater sampling around the angling area for this study. Although the food items of the fish changed slightly with season and age-group, main food items were Amphipoda (Gammaridae, Caprellidae) and Isopoda (Sphaeromidae, Idotheidae). This suggests that the diets of A. agrammus mainly comprised epibenthic food. Food diversity increased with age. The fish almost consummed on smaller food in size, but had selective predation according to food size, i. e. on larger food as age increases. These data provide additional support for the importance of the detritus-benthos-consummer type food chain.